Vehicle safety consistently remains a cause for concern amongst vehicle manufacturers and consumers. Road departures comprise a major cause of vehicle injuries and fatalities each year. In order to address this issue, manufactures have included active stability control systems and related approaches in vehicles to prevent vehicles from driving outside the boundaries of the road. Although these approaches contain numerous advances designed to increase vehicle safety, the operator's actions are often the ultimate arbiter of whether a vehicle accident results in injury to the vehicle's occupants and others, and thus providing a timely warning to the operator of a potential road departure is crucial.
Vehicle warning systems anticipate potential impending or imminent accidents and provide warnings to vehicle operators so that the operators can take an action to avoid the accident. Previous road and lane departure systems rely on the use of road and lane markings, which are not always visible (for instance, during poor-visibility weather conditions) or present (for instance, on sidewalks, dirt roads, private roads, rural roads, and other paths). In addition, many previous road and lane departure systems only work for vehicles travelling above a certain speed. This precludes the use of these systems in non-automobile vehicles and on low-speed roads, sidewalks, paths or other roads in which high speeds are dangerous or aren't possible.
Additional road and lane departure systems rely on multiple-meter Global Positioning System (GPS) signals, which are only accurate to within several meters, which limits the ability of these systems to provide road departure warnings early enough to be useful to the operator of a vehicle. Further, relying on multiple-meter accuracy for departure warnings results in false-positive warnings, which are annoying to drivers. Such false-positive warnings may cause the operator of a vehicle to disable the warnings, thereby nullifying the effectiveness of the warnings, or may cause a consumer to avoid purchasing a vehicle equipped to provide such warnings entirely.